"Nor had we realized that patients who experience a milder or slower onset of symptoms would also exhibit a distinct help-seeking behavioral pattern, i.e. they take much longer to reach the emergency department than those with fast-onset heart attacks because they don't call an ambulance, they call/visit their doctor or they wait to see if their symptoms would go away," she told Reuters Health in an email.

By interviewing 893 heart attack patients a few days after the event, O'Donnell and her coauthors determined how quickly the patients had experienced and reacted to their symptoms.

Two-thirds had symptoms come on slowly, and the remaining one third felt severe symptoms right away.

Those with slow symptoms tended to wait three and a half hours before going to the hospital, compared to two hours for those whose symptoms came on fast, O'Donnell's team reports in the Journal of Emergency Medicine.

According to the U.S. National Heart, Lung and Blood Institute, among people who die from heart attacks, about half do so within an hour of having their first symptoms and before they reach the hospital.

Researchers aren't sure why heart attack symptom speed differs between people. It could depend on whether coronary arteries are blocked fully or partially, said Holli A. Devon, who researches how symptoms of heart problems present in different groups of people.

Devon, a registered nurse and associate professor at the University of Illinois at Chicago College of Nursing, was not involved in the study.

"Based on previous studies, including our own, women, older adults and individuals with diabetes are less likely to report chest pain, therefore they are at greater risk for ignoring symptoms that they may deem minor or non-life threatening," Devon said.

"An important message is that if you or a friend or family member has chest pain, pressure or discomfort or related symptoms such as shortness of breath, cold-sweats or pain in the shoulders or arms you should call emergency medical services immediately," she said.

"My advice is that if anyone experiences any of the worrying symptoms above, that do not resolve after 15 minutes of rest, then they should call an ambulance and go straight to the emergency room," O'Donnell said.

Calling or visiting a doctor first has been linked to treatment delays and poorer outcomes in international studies, she said.

The American Heart Association recommends calling EMS within five minutes of symptom onset. "We are missing this target by hours, not minutes. And in some cases, days," Devon said.

Sudden tightness in your chest? Shooting pain down your left arm? Everyone knows that could be a heart attack. But what if symptoms aren't so sudden?
When symptoms come on slowly, heart attack patients are less likely to get to a hospital quickly, according to a study in...